12 August 2009

Uganda: Elephant Grass Disease Threatens Milk Production


Today's Ugandan farmer apparently faces more challenges than were previously known. Our soils are becoming poorer, with an estimated top soil loss of five tonnes per hectare per annum, thanks to soil erosion.

Our country is host to far more dangerous crop and animal diseases than we were used to before. Among new diseases are coffee wilt disease, banana bacterial disease, cassava mosaic and cassava brown streak disease.

More recently, a new disease that prevents the proper growth of the Napier grass (elephant grass) known as Napier Stunt Disease came on the scene. All these new challenges have the potential to disrupt our food security plans or even reverse the entire country's economic progress.

Native to large parts of tropical Africa, Napier grass is important for its nutritive value as fodder for animals such as cattle and goats, particularly those under the zero grazing system. Napier Stunt disease causes the Napier grass leaves to turn thin, yellow, and frail. The grass stops to grow and the leaves of the affected plants begin to dry at the edges. Yellow or purple streaking normally starts at the leaf tips and eventually, the whole plant may be completely destroyed. According to Dr Jolly Kabirizi, a senior research officer and forage scientist at the National Agricultural Research Organisation (Naro), the disease is currently spreading in the districts around Lake Victoria. "It is however possible that it had struck much earlier without farmers noticing it or reporting it to the agricultural experts," she said in an interview.

Researchers at Naro and the National Livestock Resources Research Institute (Nalirri) however warn that yellowing or poor appearance of Napier grass could sometimes be due to poor soils and any abnormal Napier grass growth should first be reported to the nearest agricultural extension worker.

The disease has a significant negative effect on animal production. It increases the farmer's anxiety over the alternative fodder to feed their cows and goats, and certainly, it decreases meat and milk production.

Apart from being fodder, researchers at Naro and at Nalirri say that for a long time, Napier grass has been used as an important tool in the integrated management of stem borers of maize and sorghum due to its importance as a trap for those pests. Some people have been growing the grass for sale to farmers who keep cows or goats even when they keep no animals themselves. The grass can serve as mulch in banana and coffee farming regions. Many farmers also use Napier grass to prevent soil erosion by planting it in lines across the fields on hill slopes.

For farmers who don't have large acreages of pasture it has been recommended that they plant an acre of Napier grass which is enough to provide enough fodder to a Friesian cow. Dr Kabirizi says, "While a healthy acre of Napier grass when properly supplemented should provide enough feed to sustain one productive cow for about six months, plots affected by the disease may support the animal for less than three months, greatly reducing milk yields and family income."

The picture is threatening as studies conducted by both Naro and Nalirri indicate that over 90 per cent of elephant grass fodder fields in Uganda are infected resulting in zero-grazing farmers reducing the number of their animals to avoid buying grass.

The disease which so far has no known cure is said to be spread by the use of infected cuttings as planting material. Leaf-eating insects such as leaf and plant hoppers are among the key suspects in its spread. Some people spread it by transporting diseased planting material from one place to another.

An article on the disease in the Daily Nation (July 27, 2007) quotes Mr Simon Degelo a researcher at International Centre of Physiology and Ecology (Icipe) as saying, "Finding a disease free Napier field is difficult since it takes a long time for the symptoms to manifest on infected plants. The disease shows symptoms after about six months to one year from the time of infection."

Farmers are then advised to uproot and burn all diseased plants and replace them after six months with disease-free planting material. They should ensure they contact the extension service provider for advice on tolerant varieties and the recommended agronomic practices such as spacing, fertiliser application, and proper cutting intervals.

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